System for developing a film



May 29, T, NOR 2,747,481

SYSTEM FOR DEVELOPING A FILM iled March 22, 1954 FIGS l l 1. I :nnnuuu T I l i '1 I 5 I 1 1 II I DDDCIDUDE 1 3000\00 l I I :i!: 1 7

- INVENTOR TUROLF NURNANN ATTO R N EY United States Pat nt SYSTEM FOR DEVELOPING A FILM Turolf Normann, Gjovik, Norway, assignor to Omega Louis Brandt & Frere S. A., Bienne, Switzerland Application March 22, 1954, Serial No. 417,799

Claims priority, application Switzerland April 21, 1953 4 Claims. (Cl. 5--94) The present invention relates to a method of developing a film, in which the film is passed through a developing bath and then through a fixing bath. This method is characterized in that the concentrations and the temperatures of the said baths are chosen such that a compromise is obtained between the most rapid velocity of passage and the sharpest development of the film, the duration of immersion of the film in both baths being the same. i

The invention also relates to an installation for carrying out this method, which is characterized by two tanks arranged side by side in a case and containing a developer and a fixer respectively, and by a set of rollers adapted to guide the film through the baths, means being provided for raising the temperature of each bath to a predetermined value.

For a better understanding of the invention reference may be had to the attached drawing and to the following description of an installation embodying the invention.

In the drawing:

Figure l is a sectional view taken along the line I-I of Figure 3.

Figure 2 is a sectional view taken along the line IIII of Figure 3.

Figure 3 is a plan view, at a reduced scale, of an installation in accordance with the invention.

Two tanks 1 and 2 are arranged side by side in a case 3 and contain a developer 4 and a fixer 5 respectively. A set of rollers 6 are adapted to guide the film 7 during its passage through the installation. These rollers are pivoted at the free ends of bars 8 fixed to the cover 9 of the case 3. An inlet 10 is provided for the film 7 in a wall of the case 3. At the opposite end of the case, two sponges 11 are provided, which are adapted to summarily wipe the film 7 when it comes out of the case 3.

A hot plate 12 is supported by means of feet 13 on the bottom of the case 3 and is connected by means of wires 14 to a source of electricity. Between the tank 1, containing the developing bath 4, and the hot plate 12 there is inserted a plate 15 of a semi-heat insulating material which poorly conducts heat. On the other hand, the tank 2, which contains the fixing bath 5, is separated from the hot plate 12 by a plate 16 of a heatconducting material. A thermostat 17, connected by means of wires 18 to the supply circuit of the hot plate 12, is fixed to the cover 9 of the case 3 and is immersed in the fixing bath 5 so as to keep its temperature substantially constant.

Both tanks 1 and 2 project outside the case 3, as shown in Figures 2 and 3, so that at every moment the levels of the baths 4 and 5 can be checked. An opening 19 is provided in a wall of the case 3 so as to give passage to the liquid of each tank. This arrangement offers in addition the advantage that the tanks 1 and 2 can be filled and emptied without the case 3 having to be opened.

After being exposed, the film 7 enters the case 3 through the inlet 10. It goes first through the develop- Patented May 29, 1956 ing bath 4 and then through the fixing bath 5, whereafter it passes between the sponges 11 before going out of the case 3.

The conventional development of a film requires a certain duration of immersion of the film, which is not the same for the developing bath and for the fixing bath. This duration also varies with the temperatures of the said baths. If the solutions are more or less diluted and if the temperature of each bath is suitably chosen, it is possible to obtain a compromise between the most rapid velocity of passage and the sharpest development of the film. This result is achieved by means of the installation as shown and described. The developing bath 4 remains at a temperature which is lower than that of the fixing bath 5, owing to the insertion of the badly conducting plate 15.

Preferably, the temperature of the developing bath 4 is maintained between 34 and 40 C., and that of the fixing bath 5 between 40 and 46 C., but these values may be greater or lower than these limits.

In a particular example of carrying out the method of the invention, the developing bath 4 contains 350 grams of the product sold under the trade name Kodak Developer Powder for 1125 cm. of solution, whereas the fixing bath 5 contains 275 grams of the product sold under the name Kodak Fixer Powder for 1125 cm. of solution. These values are not limitative.

The film 7 is advanced by hand traction and the result of the development determines the speed at which the film should be drawn. This advancing movement could of course also be effected automatically with the help of a motor. Preferably, the speed of passage of the film through the baths lies between 20 and 30 cm./min., but may be greater or less than these limits.

The invention is advantageously applied to the development of the films used in certain time-keeping apparatus comprising a camera, such as for instance the apparatus disclosed in my co-pending application Serial No. 417,798, filed at the same date. It enables one to obtain within an extremely short time the registered results. It is to be understood, however, that the invention is not limited to this particular application.

While the invention has been described and illustrated with reference to a specific embodiment thereof, it will be understood that other embodiments may be resorted to without departing from the invention. Therefore, the form of the invention set out above should be considered as illustrative and not as limiting the scope of the following claims.

I claim:

1. A film processing device through which a film is adapted to be drawn to subject the film successively to two processing liquids, comprising, in combination, a hollow casing formed with a film inlet and a film outlet, two tanks arranged side by side in the casing and containing a developing bath and a fixing bath respectively, a set of rollers adapted to guide the film through the baths, an electrically heated plate arranged at the bottom of the casing, a semi-heat insulating plate and a heat conducting plate supported by the said electrically heated plate, the developing tank supported by the said semiheat insulating plate and the fixing tank supported by the said heat-conducting plate, so that the fixing bath is heated to a temperature higher than that of the developing bath, a thermostat connected to the supply circuit of the electrically heated plate, the said thermostat immersed in the fixing bath, both tanks projecting outside the casing so that the levels of the baths can be checked, and a film wiper positioned at the said casing outlet to wipe the film as it leaves the casing.

2. A film processing device through which a film is adapted to be drawn to subject the film successively to two processing liquids, comprising, in combination, a hollow casing formed with a film inlet and a film outlet, two tanks arranged side by side in the casing and containing a developing bath and a fixing bath respectively, a set of rollers adapted to guide the film through the baths, an electrically heated plate arranged at the bottom of the casing, a semi-heat insulating plate and a heat conducting plate supported by the said electrically heated plate, the developing tank supported by the said semiheat insulating plate and the fixing tank supported by the said heat conducting plate, so that the fixing bath is heated to a temperature higher than that of the developing bath, both tanks projecting outside the casing so that the levels of the baths can be checked, and a film wiper positioned at the said casing outlet to wipe the film as it leaves the casing.

33. A film processing device through which a film is adapted to be drawn to subject the film successively to two processing liquids, comprising, in combination, a hollow casing formed with a film inlet and a film outlet, two tanks arranged side by side in the casing and containing a developing bath and a fixing bath respectively, a set of rollers adapted to guide the film through the baths, an electrically heated plate arranged at the bottom of the casing, a semi-heat insulating plate, and a heat conducting plate supported by the said electrically heated plate, the developing tank supported by the said semiheat insulating plate and the fixing tank supported by the said heat-conducting plate, so that the fixing bath is heated to a temperature higher than that of the developing bath, both tanks projecting outside the casing so that the levels of the baths can be checked.

4. A film processing device through which a film is adapted to be drawn to subject the film successively to two processing liquids, comprising, in combination, a hollow casing formed with a film inlet and a film outlet, two tanks arranged side by side in the casing and containing a developing bath and a fixing bath respectively, a set of rollers adapted to guide the film through the baths, an electrically heated plate arranged at the bottom of the casing, a semi-heat insulating plate' and a heat conducting plate supported by the said electrically heated plate, the developing tank supported by the said semiheat insulating plate and the fixing tank supported by the said heat conducting plate, so that the fixing bath is heated to a temperature higher than that of the developing bath.

References Cited in the file of this patent UNITED STATES PATENTS 1,923,108 Mehl Aug. 22, 1933 1,967,889 Kitroser July 24, 1934 2,475,973 Luboshez July 12, 1949 2,618,210 Mayer Nov. 18, 1952 FOREIGN PATENTS 470,197 Great Britain Aug. 11, 1937 OTHER REFERENCES Hewston: Journal of Society of Motion Picture dz Television Engineers, vol. 56, No. 6 (Part I), June 1951, pp. 613 thru 622. 

